APPENDIX A: CRASH TYPES AND COST LEVELS TABLES

Based on the past work by Miller et al., the needs of the red-light-camera evaluation effort, and projected needs in future FHWA safety studies, the decision was made to estimate human capital and comprehensive costs for each of the following 22 geometry categories. The geometry names used in the output tables are shown in parentheses.

In the original analyses, multiple-vehicle, cross-path categories 7, 8, and 9 above were further categorized by turning maneuver-"both vehicles straight," "one turn right," "one turn left," or "unknown direction." These were later combined into the larger categories due to sample size.

Note that some of the rows in the table are coded 'S', 'I', or 'N' under the code column. All three codes are included as "flags" to the user that these estimates are felt to be less accurate than estimates in other rows. The 'S' coded rows indicate estimates that were derived from small sample sizes.

The 'I' coded rows indicate what are felt to be "illogical values" or "outliers" in the data-cells with ample sample sizes, but where the cost for a given injury level is an outlier when compared with either other costs within the same crash type (e.g., a B+C cost that is greater than an A-injury cost for a given crash type), or when compared to costs of different crash types at the same injury level (e.g., a no-injury cost that is much greater than all other no-injury costs). These illogical estimates were identified by looking at patterns of costs in similar severity levels or crash types. Since it was not possible to examine each illogical finding in detail, they were flagged for the user's benefit. Again, suggestions for dealing with these are found in the next section.

In addition, there are crash types in the NASS data used to develop these estimates where no fatal crashes were present. For example, if the comparable "Level 1 w SL" table had been presented here, the user would note the absence of a crash cost estimate for fatal crashes within the Type 3, single-vehicle animal crashes. No such fatal crash existed in the NASS data used to develop these estimates. All combined estimates (e.g., K+A, K+A+B, K+A+B+C) with no fatal component are coded 'N' in the tables.